Authentication

Abstract

Billy left home when he was in his teens and went to seek his fortune in Australia. When he returned home 30 years later as a mature, successful man, his relatives came to meet him at the dock in Southampton. He later remarked on this meeting to a friend “after not having seen my mother for 30 years, I have recognized her instantly among my many aunts, uncles, and other family.” This short (and usually true) story illustrates the use of identification and authentication in real life. We authenticate a person by looking at them and listening to them, and we can do this even after a long interval during which the person has greatly changed. A computer, unfortunately, cannot see its owner/user and has to rely on other means for authentication, which is the topic of this chapter.